Gas release mechanisms



June 18, 1963 L. E. GOFF GAS RELEASE MECHANISMS 3 Sheets-Sheet 1 FiledAug. 31, 1960 Q. @m. mm mm,

om 1m INVENTOR.

LIONEL E. GOFF Y k/hwzib ATTORNEY June 18, 19 63 E. GOFF 3,094,070

GAS RELEASE MECHANISMS Filed Aug. 31, 1960 3 Sheets-Sheet 2 INVENTOR.LIONEL E. GOFF A TTOIPNEY June 18, 1963 GOFF GAS RELEASE MECHANISMS 3Sheets-Sheet 3 Filed Aug. 31, 1960 y .74 v M ow W INVENTOR. LIONEL E.GOFF ATTORNEY United States Patent 3,094,070 Patented June 18, 1963iifice 3,094,070 GAS RELEASE MEQHANHSMS Lionel E. Goif, Aiton, liL,assignor to @lin Mathieson Chemical Corporation, East Alton, 11L, acorporation of Virginia Filed Aug. 31, 1960, Ser. No. 53,218 1 Ciaim.(Cl. 1102-45) This invention relates to gas release mechanisms and moreparticularly to such devices adapted to eifect the sudden release of acharge of compressed gas to serve as a work performing medium. Whilesuch devices are applicable to many commercial applications, the presentinvention will be described with particular reference to blastingcartridges utilizing compressed gas. This application is acontinuation-in-part of Serial No. 828,812 filed July 22., 1959, nowabandoned.

Material breaking cartridges using compressed gas to execute therequired work are well known and widely used in the mining industry.Such cartridges or blasting devices are all reliant upon the suddenrelease of compressed gas to give a quasi explosive effect. Thepredecessors of this type of blasting cartridges consisted essentiallyof a cylindrical gas containing cartridge having venting means. Thecartridges were charged with gas under considerable pressure, sealed andthen conveyed to the face to be worked. The compressed gas within thesecartridges was released by elaborate remote control means. Morerecently, the practice has been to place an uncharged cartridge in thebore hole and pump gas through a suitable conduit into the cartridge insitu. Conventionally, these cartridges are formed of high strengthmaterials and are provided with a relatively Weak member which shears orruptures so as to liberate the gas from the cartridge body. Since theamount of pressure that can be built up in the cartridge body isdependent upon the strength of the expendable member, the quantity ofenergy developed by the liberation of the gas can be controlled withinrelatively close limits. Such cartridges are generally satisfactory buthave one serious inherent drawback. After each shot, the discharge endof the cartridge must be dismantled to remove the exendable portionwhich has ruptured or sheared and to replace it with a new one.

This shortcoming has been well recognized and has led to a concertedeffort for the development of automatic shells. While many so-calledautomatic shells have been presented, they have met with only a modicumof success. The previous types of automatic cartridges are operable, butthey are very heavy, complex and unreliable. Although the expendableportions of the shell have been eliminated, this elimination hasintroduced new and more serious problems. Normally, the known automaticshells rely upon a series of two or more control or pilot valves toinitiate the main release valve. Such complexity of design leads tocartridges that are difficult to control and exceedingly difficult todischarge at a desired predetermined pressure. In addition, the greatnumber of moving parts in the automatic shells prior to the advent ofthe present invention has confronted the industry with a formidablesealing problem.

Therefore, it is an object of this invention to provide new and improvedautomatic or semi-automatic devices for releasing compressed gas. Afurther object is to provide a device of this character having novel gasre lease means. Another object of this invention is to provide asimplified automatic or semi-automatic blasting shell overcoming thedisadvantages of the prior art.

The manner in which these and other objects are achieved will beapparent from the following specification together with the dravw'ng inwhich:

FIGURE 1 is a longitudinal sectional view of a device illustrating apreferred embodiment of this invention;

FIGURE 2 is a longitudinal sectional view of a modification of thedevice shown in FIGURE 1;

FIGURE 3 is a longitudinal sectional view of a device illustratinganother embodiment of the present invention;

FIGURE 4 is a longitudinal sectional view illustrating an additionalmodification of the present invention;

FIGURE 5 is a longitudinal sectional view illustrating still anotherembodiment of the present invention; and

FIGURE 6 is a longitudinal sectional view of another modification ofthis invention.

The same numbers are used throughout the drawing to identify similarcomponents.

Referring to FIGURE 1 which illustrates a preferred embodiment of thepresent invention, an elongated tubular body formed of metal, fiberglass reinforced plastic, or other material of a strength to contain gasunder high pressures, for example in the range of from 6,000 to 20,000pounds per square inch, is indicated generally at 1. Suitable means suchas a compressed air inlet 48 are provided at one end of the cartridgebody for introducing compressed gas into it. The outer diameter of thebody is such that it may be set freely within a bore drilled in the faceof the material, such as coal, to be mined and broken down. The end ofthe body 1 remote from the gas inlet is screw threadedly attached tosleeve 2 as indicated at 3. The seal between these two components iscompleted by resilient O-ring 4. The other end of the sleeve is closedwith end plug or cap 5 which is screw threadedly attached to sleeve 2 asindicated at 6 with the seal between these two members also beingcompleted by resilient sealing means, such as O-ring '7. The interior ofthe cylindrical body is divided into a main chamber 8 and a secondchamber 9 by main valve 10 which is slidable in the body. The valve isnormally maintained in a closed position spanning lateral dischargeports 11 by helical spring 12 positioned in annular space 13 betweensleeve 2 and central extension 14 of end cap 5. The valve is slidablysealed to the central extension 14 of the end cap by resilient sealingmeans, such as O-ring 15.

As shown in the drawing, the base portion 16 of the valve is providedwith a passageway 17 so as to maintain the pressure within chambers 8and 9 substantially equal while the chambers are being charged withcompressed gas. Valve 10 is also provided with one or more lateral vents18 in the area of reduced diameter adjacent the base of the valve. Thevalve is normally held in sealing relationship with metallic seal ring19 which is slidably sealed to sleeve 2 by suitable resilient means suchas O- ring 20. Metallic sealing ring 10 is responsive to the pressuresbuilt up within main chamber 8 but is restricted in its movement by itsabutment with tubular body 1 and also by shoulder 21 of sleeve 2. Asshown in the drawing, the sealing ring 19 terminates in a modified knifeedge 22 at its point of contact with shoulder 23 of the sleeve valve.The knife edge is carefully machined and polished or otherwiseconstructed to insure the formation of a metal-to-metal seal between themetallic sealing ring and the valve. Although such a knife edge ispreferred, the forward end of the ring 19 can be otherwise constructedsuch as square so as to provide a flat metal-tometal seal with shoulder23 of valve 10.

While the sealing ring 19 is shown as a member separable from andmovable in relationship with main body 1, the ring can be rigidlypositioned between the main body and shoulder 21 on the sleeve.Alternately, the inner portion of main body 1 of the cartridge can bemodified to form an immovable valve seat for main valve 10. With suchconstruction, it is necessary to maintain the proportions and designsuch that an effective seal with valve 10 is had during the gas chargingoperation. Be-

cause of minor inherent surface irregularities, the construction is suchthat the enlarged basal portion of the metallic sealing ring 19 and theend of body 1 do not form a seal. Thus, under the high pressuresencountered, the entire base surface of metallic sealing ring 19 issubjected to the pressure within main chamber 8.

The internal diameter of metallic seal ring 19 is larger than theoutside diameter of the basal portion 16 of the valve 10 so as to form asmall clearance between these two components. If this clearance is madesufficiently large, suflicient air from the main chamber will passtherethrough into the second chamber 9 so as to equalize the pressurewithin these two chambers. In such instances, passageway 17 in the baseportion of the valve 119 can be eliminated.

The cartridge of this embodiment is so designed that the valve 11 has agreater effective area exposed to the gas pressure in the main chamber 8than to the gas pressure in the second chamber 9. Also, the effectivearea of the metallic sealing ring 19 exposed to gas pressure is greaterat that end proximate the main body 1 than at the other end. Thesedifferential areas of valve 16 and metallic seal ring 19 cause them tomove in a direction away from the main body 1 as the pressure within thecartridge is increased.

In operation, compressed air or other suitable gas is introduced intomain chamber 8 through gas inlet 48. The air passes through passageway17 and lateral vents 18 in main valve 11) into the second chamber 9.Thus, the pressure on either side of main valve 10 is substantiallyequalized and is maintained equal throughout the charging operation.Because of the greater effective cross-sectional area of valve 1%]! andmetallic seal ring 19 in the main chamber than in the second chamber,the valve and the ring are urged in a direction toward end cap 5 inopposition to helical spring 12.

This sliding movement of valve 16 and seal ring 19 continues until apredetermined discharge pressure, for example about 9,080 pounds persquare inch, has been built up in chambers 8 and 9. At this point,further movement of the metal seal ring 19 is prevented by its contactwith shoulder 21 on sleeve 2. Continued movement of the valve 119 causesa separation of the valve from the metallic seal ring 19. Thisseparation has two instantaneous effects: an increase in the effectivearea of the main valve exposed to the pressure in main chamber 8, and areduction of gas pressure in chamber 9 by gas being vented throughlateral vents 18 and exhaust ports 11. Thus, the pressure in secondchamber 9 is reduced at such a rapid rate that it cannot be balanced bygas from the main chamber entering through passageway 17 and/or fromaround the periphery of 16 through lateral vents 18. The pressure in themain chamber 8 is thus suddenly unopposed and the main valve 10 is movedrapidly unsealing lateral discharge ports 11. Any compressed gasremaining in the second chamber 9 is exhausted through lateral vents 13and exhaust ports 11. With the sudden reduction of pressure within thesecond chamber 9, the charge of compressed gas in main chamber 8 iscompletely and instantaneously released through ports 11 to thesurrounding work face which is to be broken down.

Upon discharge, the annular space 13 between central extension 14 of theend cap and sleeve 2 serves as an air cushion which prevents the valve10 from setting up disruptive forces upon discharge by coming in contactwith the end of the cartridge. While the air within this annular spacedoes serve as a cushion, it does not hinder the opening of the valvebecause the compressed air can escape at a reduced rate through theannular clearance 24 between the outside diameter of valve 10 and sleeve2.

After the compressed gas in main chamber 8 has been completelydischarged, the valve is returned to its original position by helicalspring 12. This also causes the mei tallic seal ring 19 to be againabutted on the end of tubular body 1. The device is then in position foranother discharge. Thus, this embodiment of the present invention iscompletely automatic.

The embodiment illustrated in FIGURE 2 is similar to that of FIGURE 1but differs therefrom in a number of respects. It will be noted thatvalve 10 is slidably sealed to sleeve 2 by means of resilient O-ring 25rather than being internally sealed to central extension 14 as was thevalve of FIGURE 1. Also, the clearance between metallic seal ring 19 andthe basal portion 16 of the valve 10 has been materially reduced. Thus,substantially all of the compressed gas entering second chamber 9 frommain chamber 3 passes through passageway 17 in the base of the valve 19.In addition, the configuration of valve 10 is modified. It is providedwith a lateral extension 27 which abuts metallic seal ring 19, and theexternal diameter of the valve above and below this extension issubstantially the same.

The cartridge of this embodiment functions in substantially the samemanner as described above. As the pressure in chambers 3 and 9 isincreased to the predetermined discharge pressure, metallic seal ring 19is stopped from further sliding movement by shoulder 21 on sleeve 2while the valve continues its sliding movement breaking the seal betweenthese two members. Here again, valve 10 is suddenly opened by the rapidreduction in pressure in chamber 9 by gas escaping through lateral vents18 and ports 11 and also by the increase in the effective area of thevalve in contact with the pressure in main chamber 8. The valvecontinues its sliding action to a fully opened position at which pointextension 27 on the valve contacts shoulder 26 on the inside surface ofsleeve 2. Disruptive contact between the valve and sleeve is preventedby gas which is temporarily trapped within annular space 28 between thevalve and the sleeve. This delaying action of the annular space istransitory because the gas can escape at a reduced rate betweenextension 27 and sleeve 2 and thus be exited through lateral dischargeports 11. Here again, the action of the shell of this embodiment iscompletely automatic and the valve and seal ring are returned to theiroriginal closed position by helical spring 12. Here, again as in theembodiment of FIGURE 1, passageway 17 may be omitted and the clearancebetween sealing ring 19 and basal portion 16 of the valve can be madesufliciently large to substantially equalize the pressures in chambers 8and 9 during a charging operation but insufhciently large to permit suchequalization of pressures when the seal between ring 19 and extension 27is broken by movement of valve 10.

In the embodiments shown in FIGURES 3 through 5, the main valve 11 isprovided with lever or triggering means to accentuate and accelerate theseparation between the valve 10 and the metal seal ring 19. In theembodiments of FIGURES 3 and 4, linkages are provided to momentarilyarrest or reduce the closing influence of springs on the sleeve valve.In the embodiment shown in FIGURE 5, the separation of these twocomponents is accelerated by a lever linkage cooperating with the basalportion of the sleeve valve. Such lever mechanisms insure a rapidlyaccelerated breaking of the seal between the sleeve valve and themetallic seal ring, even at rather low pressure levels or when thedifferential areas of the valve and metallic seal ring are at a minimum.The embodiments illustrated in these three figures will now be describedseparately.

In the embodiment illustrated in FIGURE 3, means have been added tointerrupt the closing influence of springs on valve 10. In thisembodiment, the end of the sleeve valve 10 remote from the basal portion16 thereof is spanned by disc 29 having one or more perforations 3t andthe valve is slidably sealed to sleeve 2 by O-ring 25. Bolt 31 passingthrough disc 29 terminates in clevis 32 which is connected to springplate 33 through con necting link 34 and pivot link 35 as shown. Thesemembers are so connected that pin 36 is slightly below the axis of pins37 and 38. Thus, any movement of valve 10 and the action of controlspring 39 tends to rotate pivot link 35 in a counterclockwise directionso as to lock the linkage. The pivot link 35 is provided with anextended portion til adapted to cooperate with stop pin 4-1 whichextends across the internal portion of sleeve 2 and is rigidly affixedthereto by any suitable means. Control spring 39 is affixed to springplate 33 as indicated generally at 42. In addition to central extension14, end cap 5 is also provided with a tubular extension 43. These twoextensions of the end cap serve as guides for helical spring 12 and alsofor control spring 39.

In operating the cartridge shown in FIGURE 3, gas is introduced throughgas inlet 43. During charging of the cartridge, the pressure withinchambers S and 9 as well as in the spring chamber to the right of thevalve is maintained substantially equal by virtue of passageway 17 inthe base of valve it) and passageways 363 in plate 29. Since theeffective cross-sectional area at the right end of valve id is greaterthan its effective area on the left end, the valve is urged toward theleft as gas pressure increases. Likewise, metallic seal ring 13 is alsopressure responsive. However, since the effective cross-sectional areaat the left end of this member is greater than at its right end, theseal ring is urged toward the right. Therefore, as the pressure withinthe cartridge approaches the predetermined discharge pressure, themetal-to-metal seal between valve 10 and metallic seal ring l9 becomesprogressively greater. The diameter of O-ring 25 is less than thediameter of O-ring 29. Thus, the seal ring and valve, taken as a unit,has a resultant cross-sectional area which is larger on the left than onthe right side. Therefore, as the pressure is increased, these membersare forced to the right.

This sliding movement continues until the predetermined dischargepressure has been attained in chambers 8 and 9. Then metallic seal ring19 is arrested in its ac tion by shoulder 21 on sleeve 2 and extensiondd on pivot link 35 is moved by stop pin 4-1. Valve 10 because of itsinertia continues movement to the right and causes a break in the sealbetween the valve and the metallic seal ring. Concurrently, extensionill on pivot link 35 is forced into a clockwise direction by stationarystop pin 41. This action unlocks the linkage between disc 29 and springplate 33. Thus, control spring 39 no longer exerts restraining force onvalve 1-9. This sudden reduction in spring pressure on the valve coupledwith the inertia of the valve facilitates breakage of the seal betweenthe metallic seal ring and the valve. When this seal is broken, thecompressed gas in second chamber 3 is rapidly vented through lateralvents 13 and exhaust ports 11, and the eifective area of valve it? inmain chamber 8 is suddenly increased. These factors insure the rapidevacuation of compressed gas from second chamber 9 and the subsequentand substantially instantaneous opening of the valve at a greatervelocity so as to permit the charge of gas Within main chamber 3 to besuddenly and efficiently expelled through lateral exhaust ports 11.After the cartridge has been discharged, pivot link 35 is returned toits original locked position by tension spring 44 extending between pins4-5 and 4-6 on the spring plate 33 and pivot link 35, respectively.Also, the valve and seal rings are urged to closed position by springs12 and 33.

The embodiment of FEGURE 4 is also provided with triggering means butpermits the employment of only one spring for operation of both the mainvalve and the triggering means. In this embodiment, disc 29 is held inplace over the end of valve 19 by helical spring 12, and is providedwith one or more perforations 36 to perrnit free passage of compressedgas therethrough. The disc is functionally connected to spring plate 33by means of connecting link 34 and pivot link 35 in substantially thesame manner as described above with regard to the embodiment of FIGURE3. The connecting link is joined to clevis 32 by pin 38 and to the pivotlink 35 by pin 36, and the pivot link is rotatable about pin 37 throughwhich it is attached to spring plate 33. Spring plate 33, which ispositioned intermediate the ends of helical spring 12 is also providedwith one or more orifices 47 to permit free passage of compressed gastherethrough.

While spring 12 is shown as a single spring, that portion of the spring121 positioned between disc 29 and spring plate 33 can be a separatespring rather than a continuation of the main spring.

In the operation of the embodiment of FIGURE 4, compressed gas isintroduced into main chamber 8 and passes through passageway 17 andabout seal ring 19 into the second chamber 3 and thence through theperforations and 47 in disc 29 and spring plate 33, respectively. Thus,the pressure, throughout the system is maintained substantially equalduring chargingj The effective areas on either side of the metallic sealring and valve have substantially the same relationship as the samemembers in the embodiment illustrated in FIGURE 4. Here again, thesealing pressure between these two members increases with increased gaspressure. However, the diameter of seal 25 on valve 10 is less than thediameter of seal 26 on metallic seal ring 19. These two members thusslide to the right as the pressure is being built up with the cartridge.This movement of the valve also causes a like sliding movement of pivotlink and spring plate 33. The linkage continues moving to the rightuntil extension 49 on pivot link 35 moves rigid stop pin 41 beforemetallic seal ring 19 contacts shoulder 21 of sleeve 2. The pivot link35 is thus rotated in a clockwise direction about pin 37 and the linkageis unlocked at the predetermined discharge pressure by pin 36 beingrotated to a position slightly above the axis defined by pins 37 and 33.With this unlocking of the linkage, the spring compression on plate 29is released for a very short period of time, causing the inertia ofvalve it to force it to the right, breaking the seal between the valveand the metallic seal ring 19 and permitting the second chamber 9 toexhaust through lateral vents 18 in valve 10 and lateral exhaust ports11. With this decrease in pressure in the second chamber 9, the force onthe left hand side of the valve is tremendously greater than the forceon its right hand side and the valve flies to the right, causing mainchamber 8 to exhaust through the ports ll and discharge the shell.

After discharge, the cartridge is returned to its original closedposition by the action of helical spring 12 and 121 on valve 10 and onmetallic seal ring 19. Also, the linkage is returned to a lockedposition by the force of spring 121 and the action of tension spring 46extending between pin 15 on the spring plate 33 and pin &7 on pivot link35. Thus, the cartridge of this embodiment is also fully automatic.

The embodiment of FIGURE 5 illustrates another means for breaking theseal between valve 1%} and metallic seal ring 19 at the predetermineddischarge pressure. In this embodiment, both the valve and the seal ringhave larger effective areas toward main chamber 8 than toward secondchamber 9 and the pressure in these two chambers is equated by gaspassing between the ring and the valve through lateral vents 18 into thesecond chamber. Thus, as the pressure within the cartridge is increased,the valve 10 and ring 19 are moved to the right against helical spring12. The base portion 16 of valve 10 is provided with a flanged member ora centrally positioned bolt 43 having an enlarged head portion 49.Metallic seal ring 19 is also provided with an internal flange 50 at thebase thereof. One or more lever members or rods 51 engage head portion49 of bolt 48 and flange 53 of seal ring 13 and are rotatable aboutfulcrum 52. As shown, fulcrum 52 is a pin passing through the mainchamber 8 proximate the base of the valve and is suitably affixed to themain body 1. However, any other suitable means can be readily employedfor rigidly positioning the fulcrum.

In the operation of this embodiment, compressed gas is introduced intothe main chamber. The gas pressure in the second chamber is maintainedsubstantially equal to that in the main chamber, as previouslydescribed, by the gas passing between valve 10 and ring 19. As the gaspressure is increased Within the cartridge, both the valve 10 and ring19 are urged to the right compressing helical spring 12. As this slidingaction continues, enlarged head portion 49 of bolt 50 engages the endportion of rod 51 causing it to rotate in a clockwise direction aboutfulcrum 52. This rotation causes the other end of rod 51 to move flange50 on ring 19 forcing it to the left, and at the predetermined dischargepressure, effects separation of the valve from the seal ring. At thispoint, chamber 9 is evacuated as described hereinbefore, and thepressure in main chamber 8 forces valve 10 very rapidly to the rightexposing lateral exhaust ports 11. Thus, the charge of compressed gascontained within main chamber 8 is suddenly liberated through theexhaust ports 11.

After being discharged, the valve and seal ring 19 are returned to theiroriginal position by the action of spring 12. As the valve returns to aclosed position, it contacts the centrally located end of rod 51,returning it to its closed position at an angle substantially transverseto the longitudinal axis of the cartridge. The proportions of rod 51 oneither side of fulcrum 52 can be readily modified to insure that theseal ring 19 will be separated from valve 10 at any point in the travelof the valve toward the right. This with the tension used on spring 12provides a convenient method for modifying the discharge pressure of thecartridge.

The cartridge shown in FIGURE 6 is similar in some respects to the oneshown in FIGURE 3 and previously described. However, the compressed gasin this embodiment does not pass to the right of valve 10. The valve isclosed at one end by plug 49 which, for example, is screw threadedlyinserted into the valve as shown at 50. The seal between the plug andthe valve is completed by resilient O-ring 51. Pivot link 34 isconnected to plug 49 through clevis 32 in the manner previouslydescribed.

When compressed gas is introduced into main chamber 8 through gas inlet48, the gas passes into chamber 9 through openings 17 and 18 in valve10. Thus, during charging of the cartridge, pressures in these twochambers are substantially equal. Since the pressure in the springchamber to the right of plug 49 is substantially atmospheric, anyincreases in pressure within the cartridge causes sealing ring 19 andvalve 10 to be urged to the right. These two members move as a unittoward end cap until metallic sealing ring 19 is interrupted in itsaction by shoulder 21 on sleeve 2. The extension 40 on pivot link 35 isin contact with stop pin 41 and continued movement of valve causes thispivot link to move in a clockwise direction and the pressure exerted onthe valve by spring 39 is thus suddenly terminated. This reduction inspring pressure coupled with the inertia of valve 10 which is enhancedby the weight of plug 49 causes the metal-to-metal seal between thevalve and the metallic seal ring to be broken. The relatively smallamount of gas in second chamber 9 is thus rapidly vented through lateralvents 18 and exhaust ports 11, whereby the pressure in chamber 9 isreduced to a value well below that in chamber 8. Simultaneously, theeifective crosssectional area of the valve exposed to the pressurewithin chamber 8 is substantially increased. The valve is thus veryrapidly opened and the gas within the cartridge is rapidly liberated, soas to provide a quasi-explosive effect. When the cartridge hasdischarged, it is returned to its original position by springs 12 and 39as previously described in connection with the embodiment of FIG URE 3.

When the valve slides to the right the gas in the chamber accommodatingsprings 3.2 and 39 is slightly compressed, and thus offers slightlyincreasing resistance to the action of the valve. The effect of thiscompression is practically negligible and if desired can be eliminatedby removal of O-ring 51 from about the outside diameter of valve 10.Then any gas trapped in the chamber can readily escape to the atmospherethrough lateral discharge ports 11.

The discharge pressure of the cartridges of the present invention can bereadily controlled by the strength of the main spring and also by theamount of tension on it which can be modified by adjustment of theposition of end cap 5 with sleeve 2 or by inserting shims between theend cap and the spring. Also, the spring can be replaced by othersuitable resilient means and various types of valves and linkage arereadily adaptable to the cartridges of the present invention. Inaddition, the linkages shown in FIG- URES 3 and 4 can be positionedcompletely within the valve when a shortened discharge portion isdesired.

Although specific elements of the invention have been described inconnection with particular embodiments, it will be readily understoodthat the various elements can be utilized in each of the variousembodiments. For example, the lever means of FIGURES 3 and 4 can readilybe incorporated with the valve structure of FIGURE 1. Also, the levermechanism of FIGURE 5 can be used in conjunction with the trigger meansshown in FIGURES 3 and 4.

While the invention has been described with particular reference toblasting or coal breaking cartridges, it will be readily appreciatedthat it is also applicable to any pressure release device in which acharge of compressed gas is suddenly liberated to act as a workperforming medium. Such devices include metal working and shapingdevices, cutting devices, power cartridges, and the like.

Although the invention has been described in considerable detail in theforegoing for the purpose of illustration, it is to be understood thatsuch detail is solely for that purpose and that many modifications canbe made without departing from the spirit and scope of the invention.

What is claimed is:

A valve device for explosively liberating a charge of compressed gascomprising a substantially cylindrical housing having a main chamber andan adjoining second chamber operative to contain gas under pressure, alateral port in said housing, a slidable two-piece sleeve valve assembly in said housing said valve assembly including a main valve and aseal ring normally in abutting relation, said main valve including ahead portion concentrically positioned in said seal ring, said headportion having lateral ports adapted to communicate with the lateralport in said housing upon separation of said main valve and said sealingring, a passageway in said main valve to equalize pressure in said mainand second chambers dur ing charging, means cooperating with saidhousing and the valve assembly normally biasing and releasably holdingthe assembly in a position which closes the said housing port, saidvalve assembly having faces of differential area effective to cause saidassembly to move as a unit in a first direction in response to fluidpressure impressed upon said faces, means cooperating with said housingand with said seal ring of said valve assembly operative to stop motionof said seal ring to break the unity of the assembly and therebyincrease the effective differential area of said main valve, said mainvalve of the valve assembly being operative by virtue of its inertia andincreased effective area to continue to move in said first directioneffective to open said port.

References Cited in the file of this patent UNITED STATES PATENTS2,083,736 Noble June 15, 1937 2,502,694 Armstrong Apr. 4, 1950 2,625,104Bugg Jan. 13, 1953 2,720,167 Hesson Oct. 11, 1955 2,794,395 Hesson June4, 1957 3,022,730 Filstrup Feb. 27, 1962

